In an Ethernet automatic protection switching (EAPS) system, loops are prevented in a layer-2 network having a ring topology. An EAPS domain includes a control virtual local area network (VLAN) and at least one protected data VLAN. The EAPS domain is associated with a master node which is linked to at least one transit node in a ring network.
When a network failure is detected on the ring, the master node in an EAPS system receives control messages over the control VLAN, the control messages indicating the network failure. During normal operation, the master node blocks the protected data VLAN traffic from traversing its secondary port. During a network failure, the master node unblocks its secondary port and reroutes the protected data VLAN traffic through its secondary port. The secondary port is re-blocked once the failure has been fixed. Each time the secondary port is blocked and unblocked, the forwarding databases on all the nodes in the ring are flushed.
Flushing the forwarding databases on the nodes requires that the forwarding entries and/or paths in each of the forwarding databases be relearned (e.g., automatically relearned) and/or reprogrammed (e.g., manually reprogrammed), both of which are expensive. In either case, reestablishing the forwarding databases does not occur instantaneously. In other words, there is period of time between the commencement of flushing the forwarding databases and subsequently reestablishing them. During this period of time, network connectivity can be temporarily severed and data (e.g., data frames, packets, etc.) can be dropped or lost.